


Fundamental Truths

by MirellaPryce



Category: Mortal Instruments Series - Cassandra Clare, Shadowhunters (TV)
Genre: Closeted Character, Emotionally Repressed, F/M, Family Feels, Hamilton inspired, Hiding Feelings, M/M, One-Sided Attraction, We're calling this new pairing Jazzy for a reason, What if Izzy also liked Jace when they were younger and told Alec, What-If, same kind of giving up your love for someone for someone else because they mean the world to you
Language: English
Status: Completed
Published: 2016-07-24
Updated: 2016-07-24
Packaged: 2018-07-26 11:10:20
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 2,321
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7571950
Author URL: https://archiveofourown.org/users/MirellaPryce/pseuds/MirellaPryce
Summary: <blockquote class="userstuff">
              <p>I know my sister like I know my own mind<br/>You will never find anyone as trusting or as kind<br/>I love my sister more than anything in this life<br/>I will choose her happiness over mine every time</p><p>Izzy-<br/>“You like Jace,” Alec breathes out</p>
            </blockquote>





	1. His Sister

**Author's Note:**

> I blame listening to the song "Satisfied" on repeat for an entire day. It is what led to this amazing disaster, of a world where Isabelle had a crush on Jace when she was 16 (Jace is 17 and Alec 18), and when Alec finds out, well, he's always loved his siblings more than he loves himself.

It’s only by chance that Alec notices it. People call him oblivious, but when it comes to his little sister, Alec has the ability to read her body language and facial expressions down to an art.

(It’s not quite good enough to be considered down to a science.)

They’re in training, and Alec is getting in way too many hits, considering his sister is one of their best Shadowhunters for her age. She looks away before he can reprimand her for not putting in her best effort. That’s when he notices the sigh. He barely hears it, because he made the mistake of trying to follow her gaze and spotting Jace instead.

It’s the kind of sigh that means Izzy has found a new romance.

What stands out this time is time is that Izzy hasn’t come to him yet to bore him to tears with every detail why this one’s perfect. He’s almost always the first one she tells these things to. Most likely because she knows he won’t criticize her for it or run away screaming (even if he really wants to sometimes).

When she looks back up at him, he raises an eyebrow at her. She’s barely sixteen, but she’s already perfected the patented Lightwood eyeroll and stubborn set jaw. Just for that he raises the other eyebrow, and levels her with a look he knows she can read that says _“What’s up with you?”_

She sighs eventually and doesn’t make him repeat the question verbally.

“It’s nothing. It’s stupid.” Alec knows that tone and suspects his mother has been talking to Izzy again. As much as he loves his parents, his sister and mother just butt heads on too many subjects.

Izzy refuses to say another word. Alec takes a quick glance around, and even though no one is close by, there are still enough people around that could walk over and overhear them, or worse, interrupt them. Making sure, quickly, that no one is looking at them, Alec grabs Isabelle by the arm and drags her out of the training area and down the halls until they’re in her room. He knows her well enough to know she’s more comfortable, and thus likely to talk, surrounded with her wild collection of things, than in his own purposefully Spartan room.

He locks the door and adds runes for silence and just to make the door extra secure.

When he turns back to face her, she’s sitting on the bed and awkwardly fidgeting with a bizarrely feathered pillow. That, combined with the fact, she’s not looking at him is enough to convince him this is going to be a long talk. Better she talk to him about it than their parents though. Their mom had started getting judgemental about all of Izzy’s dating even before she had started going out with Downworlders, and their dad would likely try to lecture her on sexual safety while simultaneously trying to avoid the topic of sex altogether, even if this was just a boy thing, and not even a sex thing. After about a minute of her refusing to look up at him, Alec just sighs through his nose and says, “Talk.”

She takes a few breaths, before asking, “What do you think of Jace?”

Alec flinches at that, and maybe he read the signs all wrong, and this isn’t about a crush, this is about Izzy realising her brother loves Jace the way he’s supposed to love girls, and she thinks he’s disgusting, and broken, and wrong, and-

“Is it wrong to think he’s handsome? I mean, even he thinks he’s handsome, so it’s fine to think it too, right?” Thankfully Isabelle interrupts, although it doesn’t do much to assuage his fears that somehow Isabelle knows about his ridiculous crush on his parabatai.

“Just as long as you don’t tell him to his face, I think it’s fine to think it,” Alec tries to joke. It must work, at least a little, because she smiles. “We don’t need his head to get any more inflated, or he won’t be able to fit out the door.”

“It’s just,” she fiddling with the blanket beside her now, and Alec takes that as an invitation to sit down next to her, and take her hand. It will be harder to avoid any close scrutiny up close, but it would be weirder for her if he didn’t sit with her while she told him everything. She takes his hand next and fiddles with that instead. “He’s supposed to be our brother.”

Alec forces himself to remain absolutely calm as she says it. This is beginning to sound more and more like a subtle lead up to his sister telling him she knows about his feelings for Jace, and that there is an entire list of reasons why he needs to stop having them immediately. He knows all the reasons already. He’s thought of them all.

He doesn’t say anything. He can’t. So he just squeezes his sister’s hand, wondering when she’ll pull away forever, telling him he’s an abomination. He keeps his breathing even, and wonders when he started letting his feelings get too obvious.

If Izzy has ever been good at something though, it’s talking before Alec has a chance to think too hard on something. “It’s ridiculous!” she declares loudly and suddenly, throwing her free hand up in the air. “It’s probably just because I see him all the time or something, and because puberty wasn’t completely unfair to him. I mean, what breathing girl probably hasn’t looked at Jace Wayland, and thought ‘Damn’!” Alec spins his head to look at her so fast he feels something pop, and when he does, she’s finally looking back at him, and that’s when it clicks that Izzy isn’t talking about him at all.

Izzy was referring to herself.

Izzy-

“You like Jace,” Alec breathes out, like a punch to the gut.

“No!” she shouts at him, and pushes herself away and curls into a ball, looking back at the floor. “Yes? Maybe…It’s gross right? Is this the part where you tell me I’m disgusting for thinking of my own brother this way?”

Alec’s brain is moving in high gear, but his protective and brotherly instincts take over for him, so within seconds, he’s back across the bed, and crushing her in a reassuring hug, and frantically whispering, “You’re not disgusting. Nothing is wrong with you. It’s not gross. Nothing is wrong with you for feeling this way.” Even as he whispers platitudes into her hair, his ears are ringing, and inside his head he’s screaming _Izzy likes Jace! How long has this been going on? But, I-_

He takes one look at her, and she might be sixteen, but she’s his baby sister, and he sees the helpless look in her eyes, and knows what’s going to happen before the thoughts make it from his brain to his mouth. “It’s a good match,” he says, holding her face in his hands, and ignoring his own heart breaking. “Don’t let it turn you off the idea, but mom and dad would be delighted too.” So much more than if Alec were to admit his feelings for Jace. “You’re beautiful, smart, and strong, and Jace would be an idiot to say no if you asked him out. You should do it. We’ll just have to think of a way for you to ask him out first, and then remind him what you’ll do to him if he hurts you.” He’s smiling harder than he has in a long time, and it hurt his face to smile so big, but it’s really nothing in comparison to how his chest feels right now.

Isabelle sniffles a little and laughs, “What? You’re not going to defend my honour if he hurts me Alec?”

“I’m not going to get _in your way_ ,” he emphasizes the last part by squishing her cheeks together. “I’ll tell you what though, if he ever did hurt you, I’d hold him back for you.”

This time, Izzy is the one to throw herself at him and hug him impossibly tight. He barely hears her muttered thanks in his chest, but holds her close, and shoves all his feelings as far away as he can. He knows without a doubt that in any version of this scenario he would choose the same thing, because he loves Izzy more than anything in his life, and would choose her happiness over his every time. Even in some far off, distant universe where he could tell his sister about his own feelings for Jace, he wouldn’t, because then she’d lie, and say she’s fine, just like he’s doing now, and he could never do that to her.

So he’ll bottle his feelings away, and support Izzy and Jace’s relationship as far as it will take them.


	2. Now She's His Bride

**Summary for the Chapter:**

> If I tell her that I love him  
> She'd be silently resigned  
> He'd be mine  
> She'd say "I'm fine"
> 
> She'd be lying!

**Notes for the Chapter:**

> I may or may not have gone a little overboard with creative structuring in this chapter. I just kind of wanted to emphasize how these are past events through Alec's eyes. Also the tense switch is intentional, for the only time in my life XD
> 
> This is all I have written, and I enjoy where I conclude this, but I did leave it open in case I ever feel like being more cruel in the future and moving this story into the events of the show/book where Clary shows up and then everything gets fucked from there. It probably won't happen, but I've left myself that room.

Things went fairly quickly after that.

Izzy had opted to ask Jace out on her own, and had more or less forced Alec to be elsewhere by setting him up for a separate mission, while she and Jace went on patrol together. Apparently Jace had taken it in stride in front of Izzy, and had agreed, even after she explained that she was asking him on a date, and not just to hang out as friends.

Alec was sworn to secrecy about how Jace had come to him freaked out later, because he was going on a date with Alec’s sister, _and was that okay? And were Maryse and Robert going to kick him out for dating their daughter? Where should he take her? Was it too casual to go to Taki’s or would it be too forward to go somewhere more upscale?_

Alec had laughed at the time, and forced himself not to think too hard about how he’d been the first one Jace went to about this, and trusted him with his personality behind his Jace Wayland Perfect Soldier mask. He assured his parabatai it was fine, and even got to tell him the same threat he’s told Izzy about how she’d kick his ass. They both laughed at that.

They were perfect together.

Well, not really. They were constantly on and off, either shouting at each other and slamming doors, or kissing like they needed it more than air and whispering loving words and smiling hopelessly at each other. But just as Alec had predicted, their parents were more than happy with the pair.

_(Robert had smiled cryptically and said “A Wayland and a Lightwood.”)_

 When other members of the Enclave talked about the pair, everyone said it was a perfect match, and they joked about how passionate the two must be together, given how firey they both already were alone.

Alec knew about that all too well. After months of the most awkward insomnia, Alec had barged into Jace’s room one morning, on the advice of an older Shadowhunter, and had dumped boxes of condoms over them, startling both of them awake. With a determined stare at the ceiling, he declared they could take their activities to Izzy’s room, because at least it was down the hall, rather than right next to his, and left, his face bright red.

They finally settled down after the first year when they’d decided they wanted to make this work, and their fighting was kept to a minimum now that they knew how to be a couple together, and fight together rather than against each other.

Another year after that, just before Isabelle’s eighteenth birthday, Jace came to Alec more quietly than Alec had seen him in a long time. Quiet and nervous were two things Alec had never associated with Jace Wayland until that night when he was asked for his blessing to ask his sister to marry him. Alec had thought he’d done a good job quashing all his emotions on the matter, and yet he still felt his heart break. Then they spent the rest of the night discussing why Jace was really nervous.

_It’s what’s expected. We’ve been together a long time now, and it makes sense. But what if I don’t really love her? What if what I’m feeling isn’t really love? My father always described it like it was so much bigger than this. I don’t want to hurt her Alec!_

Alec, despite everything in him screaming against it, did his best to comfort Jace, and assure him that it had to be love if Jace felt this strongly, and was more worried for Isabelle than he was for himself. He told Jace he knew them both, and that it might not be the instant love of fiction, but it was the kind they’d built together with hard work and a passion only the two of them possessed, and that it was so much stronger for it.

Before the night was over, and the sun rose over the two of them on Alec’s bed, Jace asked him one more thing.

* * *

 

That’s how Alec finds himself standing beside Jace, and watching Izzy walk down the aisle, dressed in gold, and shining like the angel. Despite everything, he’s smiling, because he loves her, and he’s so happy that if anyone can have Jace for the rest of their life, it’s her. It’s obvious they love each other, just from the way they’re smiling at each other for the entire ceremony.

They draw the marks, and the Silent Brother declares them the newly wedded Jace and Isabelle Lightwood.

_(Could I marry into your family? Could I take your name if Izzy will have me Alec? Could I really be your family?)_

Alec claps, and his parents are smiling, more proud than they would normally admit.

Alec hugs them both tightly and holds back tears, and lets go of any dreams of “What if” for the last time.

Alec has transfer papers to take him to the Madrid Institute tomorrow.


End file.
